the brainstem Flashcards
the brainstem is home to how many cranial nerves
9 of 12 cranial nerves
what are the cerebral peduncles
- corticcospinal
- corticobulbar
- corticopontine
basilar pons
- pontine nuclei
- transverse fibers of the pons
pyramids
longitudinal bundle of fibers: the corticospinal tract
the 4th ventricle overlies:
pons and medulla
what are the 3 main tracts that begin or end in the cord that course through the brainstem
- spinothalamic tract
- dorsal column nuclei
- corticospinal tract
what is the medial longitudinal fasciculus
coordinates eye and head movements
axons from the ____ nuclei project to the contralateral medial rectus motor neurons in the ____ nucleus
MLF
abducens; oculomotor
the MLF is also the route of descent for axons of the:
medial vestibulospinal tract
lesion in corticospinal tract
long tract
since a lesion in the BS is above the decussation: patient has spastic weakness contralateral and below the lesion (increase tone and increase reflexes)
lesion in medial lemniscus
long tract
since the ML contains crossed axons of the second neuron, a lesion will result in a loss of touch, vibtration, conscious proprioception contralateral
lesion in spinothalamic tract
long tract
crossed in cord - lesion results in a pain and temperature loss contralateral
what is the somatic motor function
- pontine and medullary reticulospinal tracts for posture and locomotion
- gaze centers (PPRF) for coordination of eye movements, particularly horizontal gaze and saccades
- central pattern generators that produce rhythmic signals to the muscles involved in breathing and swallowing
what does the cardiorespiratory center function do
neurons in the caudal part of the solitary nucleus respond to:
- chemoreceptors that monitor levels of CO2 and O2 in the blood
- baroreceptors that monitor changes in blood pressure
- stretch receptors in the lungs
what does the pain modulation function do
part of descending pain modulation system that can block nociceptive inputs
what does the sleep and consciousness function do
- reticular formation and small core nuclei in brainstem are part of the ascending reticular activating system (ARAS)
- this is a set of connected nuclei that are responsible for regulating wakefullness, sleep-wake transition and attention
- maintains consciousness
what systems does the sleep and consciousness function combine
- cholinergic projection
- melanin/orexin projection
- hisatminergic projection
- serotonergic projection
- norepinephrine projection
special efferent
fibers to skeletal muscle of branchiomeric origin - V, VII, IX, X, XI
special afferent
- fibers from the tongue, larynx, pharynx for taste - VII, IX, X
- fibers from the cochlear and vestibular apparatus which mediate audition and balance - VII
where are the efferent and afferent nuclei located in the brainstem
efferent are medial and afferent are lateral
what are the 3 discontinuous colomns of motor nuclei
- somatic efferent (skeletal muscle)
- visceral efferent (preganlionic parasympathetic)
- special efferent (skeletal muscle that develops in the branchial arches)
what are the superior rectus and superior oblique
axons of motor neurons are crossed
what cranial nerves are somatic efferents to skeletal muscle
CN III, IV, VI, XII
what are the functions of the oculomotor cranial nerve III
- move eyeball
- elevate the eyelid
- pupillary light reflex - constricts the pupil
what are the dysfunctions of CN III - oculomotor
- abduction and downward deviation of eye
- drooping of the eyelid
- dilated, non-reponsive pupil
what muscles does the hyperglossal nerve (XII) innervate
ipsilateral tongue muscles
what happens when there is damage to hypoglossal nucleus or nerve
the tongue deviates toward the damaged side
what are the parasympathetic visceral efferents
- nuc. of edineger westphal (III) pupil constriction near response
- superior salivatory nuc. (VII) lacrimation
- inferior salivatory nuc. (IX) parotid
what are the branchial arch motor special efferents
- motor nuc. of V: mastication
- motor nuc. of VII: facial expression
- nucleus ambiguus (IX, X): palate, pharynx, larynx muscles
what is the solitary nucleus
- taste (VII, IX, X) (SA)
- (IX, X) (VA) cardiorespiratory center: carotid sinus, carotid body
what are the functions of CN VIII - vestibulocochlear
hearing and equilibrium
what are the dysfunctions of CN VIII - vestibulocochlear
- deafness
- loss of balance (ataxia, head tilt, falling/rolling to one side, nystagmus, stabismus)
what are the 3 trigeminal nuclei
- mesencephalic nucleus: proprioception
- main, chief or principal nucleus: touch
- spinal nucleus: pain and temperature
where does CN V enter/exit
pons/ near main, chief or principal nucleus of CN VIII
